Question

The above $I-V$ graph shows the characteristics of a $p-n$ junction diode which is connected to a signal generator of the peak voltage $22V$ . The dc current across the load $4.8\Omega$ is $iA$ , then $4i=?$

Answer 1

Answer: 5

The current at $2V$ is $250mA$ and at $2.2V$ it is
$500mA.$ The dynamic resistance in this region is,
$r_d=\frac{\Delta V}{\Delta I}$
$=\frac{(2.2-2)}{(500-250)\times {\left(10\right)}^{-3}}=\frac{4}{5}\Omega$
Now, when the diode is connected to ac supply it works as a half-wave rectifier giving a dc output. For half-wave rectifier, peak current is,
$I_0=\frac{V_0}{r_d+R_L}$
$=\frac{22}{\frac{4}{5}+4.8}$
$=\frac{22}{5.6}A$
$\therefore I_{dc}=\frac{I_0}{\pi }=\frac{22}{5.6\times \frac{22}{7}}$
$=\frac{5}{4}$
$=1.25A$